Wellness comes from well (adverb/adjective, 'in good health') + the noun-forming suffix -ness, from Old English wel ('well') and -nes. The modern health-movement sense dates from the mid-20th century. In current use it is a noun meaning "the state of being in good health, especially as actively pursued". That sense is explained by the older material without requiring a speculative semantic step: the inherited or borrowed base supplies the field of meaning, while the English formation fixes its modern role. The suffix -ness turns a quality into a noun of state, condition, or degree. The surface form is compositional: its joined elements remain visible in the modern word. A central historical form is Old English wel. Related English forms include well. The word's history is thus visible in its construction: the components remain interpretable even after the whole expression has settled into a conventional English meaning.